Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- This driver used the if_watchdog timer both as a watchdog on transmit and
auto-negotiation. To make this simpler and easier to understand I have
split this out into two separate timers. One just manages the auto-neg
side of things and one is a transmit watchdog. Neither uses if_watchdog.
- Call ether_ifdetach() at the start of detach.

- Consistently use if_printf() only in interface methods: if_start(),
if_watchdog, etc., or in functions used only in these methods.
In all other functions in the driver use device_printf().
- Use __func__ instead of typing function name.

Submitted by: Alex Lyashkov <umka sevcity.net>

Fixup locking in if_my(4) and mark it MPSAFE:
- Add locked variants of my_start() and my_init().
- Assert that the lock is held in several places rather than recursing.
- Overhaul failure case handling in my_attach() so that it will actually
clean up completely in each of the failure cases.
- Setup the interrupt after ether_ifattach() in my_attach().
- Remove unused callout handle from softc.
- Free the metadata for the descriptors my_in detach() (we leaked it
before).
- Fix locking in my_ioctl().
- Remove spls.

Tested by: brueffer
MFC after: 3 days

- Use if_printf() and device_printf() instead of outputting my%d:
everywhere. This means that my_unit is no longer used as well. The
watchdog routine now also prints 'my0: ...' rather than 'm0x0: ...'.
- Don't bzero the softc and don't try to free it in detach or if attach
fails.
- A whitespace fix.

Stop embedding struct ifnet at the top of driver softcs. Instead the
struct ifnet or the layer 2 common structure it was embedded in have
been replaced with a struct ifnet pointer to be filled by a call to the
new function, if_alloc(). The layer 2 common structure is also allocated
via if_alloc() based on the interface type. It is hung off the new
struct ifnet member, if_l2com.

This change removes the size of these structures from the kernel ABI and
will allow us to better manage them as interfaces come and go.

Other changes of note:
- Struct arpcom is no longer referenced in normal interface code.
Instead the Ethernet address is accessed via the IFP2ENADDR() macro.
To enforce this ac_enaddr has been renamed to _ac_enaddr.
- The second argument to ether_ifattach is now always the mac address
from driver private storage rather than sometimes being ac_enaddr.

Reviewed by: sobomax, sam

Start each of the license/copyright comments with /*-, minor shuffle of lines

Add the driver for "myson" ethernet cards.
This driver was written by Myson and is made available
by their courtesy.
The 5.x version is not fully tested (I will be testing) but
the 4.x version has been tested by many.
I will commit it soon.
Myson have their own chip design based on the DEC 214xx family but
with several differences. Myson sells this chip to several
EOMs in teh Chinese area so there may be many noname brand cards
that respond to this driver. Myson will be supplying a list
of some of these.